PREP: Adjust rack to middle position and preheat oven to 450 degrees. Coat an 8-by-8-inch baking dish with nonstick cooking spray. Finely dice celery. Halve, peel, and mince onion. Pick sage leaves from stems; finely chop leaves until you have 1 TBSP. Strip thyme leaves from stems; finely chop leaves until you have 1/2 TBSP. (Save remaining herbs for later!) Halve buns, then cut into 1-inch cubes.

SOAK: Fill a large bowl or large liquid measuring cup with 11/2 cups warm water. Stir in dried cranberries, vegetable stock concentrate, and chicken stock concentrates. Set aside.

COOK: Melt 3 TBSP butter in a large pan over medium-high heat. Add celery, onion, and a big pinch of salt and pepper. Cook, stirring occasionally, until veggies begin to soften, 3 minutes. Stir in garlic powder, 1 TBSP chopped sage, and 1/2 TBSP chopped thyme; cook until fragrant, 30 seconds. Stir in cranberries and soaking liquid, scraping up any browned bits from bottom of pan. Bring veggie mixture to a boil, then turn off heat.

MIX: Crack egg into a small bowl; beat until combined. (TIP: You can also crack egg into the bowl or liquid measuring cup from Step 2.) In a second large bowl, combine brioche cubes and veggie mixture; season with salt and pepper. Let cool 1-2 minutes, then stir in beaten egg until well distributed. Transfer stuffing to prepared baking dish. Dice 1 TBSP butter into small pieces; sprinkle on top of stuffing. TIP: Wash and dry pan to reuse for Classic Gravy. Wash hands and surfaces after handling raw eggs. Consuming raw or undercooked eggs may increase your risk of foodborne illness.

BAKE: Coat one side of a large piece of foil with nonstick cooking spray. Cover stuffing with prepared foil, coated side down. Bake on middle rack for 20 minutes. Remove foil and continue baking until lightly browned and crisp on top, 10-15 minutes more. (Watch carefully to prevent burning.) Remove from oven and let rest 5-10 minutes before serving. ASSEMBLED THE DAY BEFORE? Bake straight from the refrigerator, covered with foil, for 25 minutes, then remove foil and bake 15 minutes more.